Methods, systems, circuits and devices for signal detection and discrimination are typically complex which increases the setup costs, the maintenance costs as well as the overall design costs of these known systems and methods. The signals inputted or otherwise provided to these known systems and method may include an AC signal or current, a DC signal or current or any combination of AC and DC signals or currents. For example, a fire alarm system may include a fire alarm amplifier configured to generate a supervised output. The supervised output may, in turn, be configured to utilize an AC signal or current to drive one or more fire alarm speakers. The supervised output may be further configured to utilize a DC signal or current during a standby condition. Thus, any device, card or automation component receiving the supervised output may be required to receive both incoming AC and DC signals or currents and discriminate therebetween.